As we saw last week, a minuscule snowfall is all it takes to grease up the roads and give scores of drivers an unexpected trip into the ditch.

The bitter cold left others sitting on the shoulder waiting for help to restart their conked-out cars.

When winter hits with such a vengeance, the seemingly benign commute can change in an instant. The best defense should be in your trunk, says Matt Hehl of AAA Minneapolis.

“The key to staying safe during winter travel is to be prepared, and the best way to be prepared is to have a winter survival kit right in your car ready to go at that moment you become stranded,” he said. “A good survival kit is one that will keep you warm and safe.”

Whether you buy a pre-made kit (AAA has a 65-piece roadside winter safety kit) or make your own, Hehl said that at minimum, every winter motorist needs a coat or blanket, boots, flashlight with extra batteries and an ice scraper. A shovel is useful to clear snow away from a vehicle and especially the tailpipe to keep fumes out should you need to run the car to keep warm. Signal flares, reflective triangles and strobe lights make it easier for rescuers to spot your vehicle.

Jumper cables are a good staple, too.

Elizabeth Flores, Star Tribune

Commuters make their way on Highway 100 as snow falls in St. Louis Park, Minn., Dec. 4, 2013.

Sgt. Jesse Grabow of the Minnesota State Patrol says a first aid kit is “an essential item” to have in your vehicle at all times. In a series of tweets last week, he also suggested items such as a plastic whistle, pocket warmers and a banner that tells passers-by to “call police.” A kit containing basic tools such as sockets, pliers and wrenches, along with a tow rope, could come in handy, he said.

Hehl says snacks such as granola bars and chocolate are necessary “to keep your energy up and stay alert.” Liquids are important, too. If you don’t have water, Grabow says to pack a metal or enamel cup and use a candle to melt snow. “Eating snow lowers internal body temperature,” he said.

Winter survival kits are not just for motorists who drive the back roads or on rural highways and freeways. Even drivers in the city can find themselves in a predicament, and help might not be fast in coming.

Last week AAA Minneapolis, which serves Hennepin County and a few adjoining suburbs, responded to more than 900 calls for help from stranded drivers on both Monday and Tuesday, three times the normal daily average.

Meanwhile, AAA Minnesota, serving the rest of the metro area, logged 896 “SOS” calls by 11:30 a.m. that Monday and projected to have 3,000 for the day, said spokeswoman Gail Weinholzer. With the plethora of calls, many motorists waited a couple of hours or longer for help. That was more than long enough to shiver.

Dead batteries were the cause of most of the calls, Weinholzer said.

Dave Bodin-Huber, manager of the Firestone Tire and Auto Center in Bloomington, said that since the cold snap hit, he has seen an influx of vehicles with antifreeze leaking, windshield wipers that don’t work and tires that don’t grip the pavement.

The message is clear: If you keep your vehicle in running order by checking the battery, tire pressure, oil levels, and heating and cooling systems, it will increase your chances of staying on the road. Yet even the most fine-tuned vehicles can slide into the ditch. A winter survival kit can help you stay safe and alive until help arrives.

Follow news about traffic and commuting at The Drive on startribune.com. Got traffic or transportation questions, or story ideas? E-mail drive@startribune.com, tweet @stribdrive or call Tim Harlow at 612-673-7768.